1. Field
One embodiment of the invention relates to a magnetic head for perpendicular magnetic recording used in a disk drive and a disk drive provided with the magnetic head.
2. Description of the Related Art
A disk drive, e.g., a magnetic disk drive, comprises a magnetic disk, spindle motor, magnetic head, and carriage assembly. The magnetic disk is disposed in a case. The spindle motor supports and rotates the disk. The magnetic head writes and reads information to and from the disk. The carriage assembly supports the head for movement relative to the disk. The head comprises a slider attached to a suspension of the carriage assembly and a head portion on the slider. The head portion is constructed including a recording head for writing and a reproducing head for reading.
In recent years, magnetic heads for perpendicular magnetic recording have been proposed to provide magnetic disk drives of higher recording densities, larger capacities, or smaller sizes. In these magnetic heads, a recording head comprises a main pole, write shield pole, and coil. The main pole produces a perpendicular magnetic field. The write shield pole is located on the trailing side of the main pole with a write gap therebetween and serves to close a magnetic path between itself and a magnetic disk. The coil serves to pass a magnetic flux through the main pole. Side shields are arranged individually on the opposite sides of the main pole in a track width direction. The side shields are magnetically coupled to the write shield pole. A part of an end portion of the main pole is located between the side shields (e.g., Jpn. Pat. Appln. KOKAI Publications Nos. 2007-294059 and 2006-252620).
A recording magnetic field is applied to the magnetic disk from just below the main pole, whereupon a recording pattern is perpendicularly recorded on a recording layer of the disk along a track of a width substantially equal to the write gap width.
In the perpendicular magnetic recording heads furnished with the side shields described above, application of magnetic fields to adjacent tracks can be suppressed. On the other hand, however, the strength of the magnetic field from the main pole that records on-track signals is reduced. Possibly, therefore, a structure may be proposed to secure the magnetic field strength by enlarging a constricted portion at the distal end of the main pole. If such a bulky main pole is combined with the side shields, magnetic fluxes that flow directly from the main pole to the side shields increase. If the magnetic fluxes leak from just below the side shields, information on the adjacent tracks may be erased or degraded. Thus, it is difficult to further improve the recording density.